- Name: Yoko
- Japanese Name: ヨーコ・Yoko
- Gender: Female
- Eye Color: Green
- Hair Color: Dark Blue
- Hometown: Twinleaf Town
- Region: Sinnoh
- Arcade Star Dahlia (possibly cousin)
- Game Counterpart:
- Dawn (Game)
- First Appearance: PT101
She was shown to be a cold person but sometimes Happy-Go-Lucky personality. Yoko admires Ash and his training methods unlike Barry's, and want to be like strong trainer like Ash.
Barry know Yoko back in Twinleaf Town; however, Yoko doesn't remember him. She only reconized Ash, Brock, Dawn, and Sapphire due to the fact that they participated in the Hearthome Tag Team Competition. She then challenge Ash to a battle to prove she is strong, but Ash came ot the victor.
After Ash defeated her she joins Ash's group until PT103. She appeared again in PT110 while she was helping Barry training.
Later, She and Barry appear in HGSS040 in the Frontier Acces meeting up with Ash and his friends also she become inspired with Gold's breeding methods. She bumps into her Cousin, Dahlia at the end of the episode. In HGSS041, she entered a Battle Tournament as part of the Twinleaf Festival in the hope battling against Dahlia, but soon lost to Barry.
Yoko decided she needs a traveling buddy which she wants Barry to take along so they appeared again in HGSS055, where she competed against Ash in a Full Sinnoh Tournament. Yoko won the match, giving her the first victory against Ash.
Yoko appears again in HGSS180 along with Barry in the Johto League Conference. After heading to the semi-finals against Ash it was knock out and lost agin to Ash. Yoko and Barry traveled to Kanto hoping to be stronger again and sometimes will Met Ash someday.